linux-kernel - Re: [PATCH RFC v2 7/7] iio: ti-adc128s052: Drop variable vref

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Message-ID: <20250405172541.641ddb39@jic23-huawei>
Date: Sat, 5 Apr 2025 17:25:41 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: David Lechner <dlechner@...libre.com>
Cc: Matti Vaittinen <mazziesaccount@...il.com>, Matti Vaittinen
 <matti.vaittinen@...rohmeurope.com>, Lars-Peter Clausen <lars@...afoo.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Nuno Sa <nuno.sa@...log.com>, Javier
 Carrasco <javier.carrasco.cruz@...il.com>, linux-iio@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2 7/7] iio: ti-adc128s052: Drop variable vref

On Wed, 2 Apr 2025 15:49:01 -0500
David Lechner <dlechner@...libre.com> wrote:

> On 4/2/25 1:10 AM, Matti Vaittinen wrote:
> > According to Jonathan, variable reference voltages are very rare. It is
> > unlikely it is needed, and supporting it makes the code a bit more
> > complex.  
> 
> There is also around 60 other drivers where we could do something like this
> in case anyone is bored. :-p

Hmm. It would be a gamble but also a nice cleanup.

We 'might' meet a case where someone notices it but seems fairly unlikely...

J
> 
> > 
> > Simplify the driver and drop the variable vref support.
> > 
> > Suggested-by: Jonathan Cameron <jic23@...nel.org>
> > Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
> > ---
> > Revision History:
> >  v2:
> >   - New patch
> > ---
> >  drivers/iio/adc/ti-adc128s052.c | 29 ++++++-----------------------
> >  1 file changed, 6 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
> > index 0f93c6266527..0bfe4e558c69 100644
> > --- a/drivers/iio/adc/ti-adc128s052.c
> > +++ b/drivers/iio/adc/ti-adc128s052.c
> > @@ -29,13 +29,12 @@ struct adc128_configuration {
> >  struct adc128 {
> >  	struct spi_device *spi;
> >  
> > -	struct regulator *reg;
> >  	/*
> >  	 * Serialize the SPI 'write-channel + read data' accesses and protect
> >  	 * the shared buffer.
> >  	 */
> >  	struct mutex lock;
> > -
> > +	int vref;  
> 
> Units in the name are helpful: vref_uv.
> 
> Could also consider doing division in probe and storing vref_mv instead
> since we never use the microvolts part.
> 
> >  	union {
> >  		__be16 rx_buffer;
> >  		u8 tx_buffer[2];  
>